Problems of direct processing of raw Ring Imaging Cherenkov (RICH) data for
the high granularity detectors of the CERES type are discussed. The robust
technique is applied to ring fitting. It is based on a least-square method
with recalculated weights depending not only on the distance of pads from
the fitted circle but also on the signal amplitudes in pads. The proposed m
ethod leads to reliable parameter reconstruction from raw data for a single
ring, as well as for two overlapping rings. Computed ring parameters are t
hen successfully used for the particle identification. (C) 1999 Elsevier Sc
ience B.V. All rights reserved.